word | definitions |
atom | the smallest particle into which an element can be divided and still retain all of that element. |
electron | the negatively charged particles found in all atoms. |
protons | the positively charged particles of the nucleus. |
neutrons | the particles of the nucleus that have no charge. |
isotope | atoms that have the same number of protons but a different number of neutrons. |
element | a pure substance that cannot be seperated or broken down into simpler substances by physical or chemical means. |
compound | a pure substance composed of two or more elements that are chemically combined. |
mixture | a combination of two or more substances that are chemically combined. |
periodic | having a regular, repeating pattern |
Periodic Law | a law that states the chemical and physical properties of elements are periodic functions of their atomic numbers. |
atomic number | the number of protons in the nucleus of an atom. |
atomic mass | the weighted average of the masses of all the naturally occuring isotopes of an element. |
Valence Electrons | the electrons in the outermost energy level of an atom. |
Halogens | elements found in group 17 of periodic table. |
Noble gases | stable, inert elements found in group 18 of periodic table. |
Ernest Rutherford | positive charged nucleus, atom mostly empty space electrons travel around nucleus. |
Nils Bohr | used the planetary model to describe the atom. |
Democritus | first to come up with the idea of an atom. |
Dimitri Mendeleev | Father of Periodic Table, arranged elements from atomic mass. |
Groups | Vertical columns on periodic table composed of similar elements with similar charges. |